(above is a picture of fun San Francisco tradition called Critical Mass in which cyclists take over the street! Thank god I don’t drive much around the city)

What does it mean to hit critical mass?
I’ve heard several pitches in which an entrepreneur outlines a marketing plan for their business which is lots of hard work, but eventually they reach a “critical mass” point where all of a sudden magic kicks in, and smooth sailing is ahead. What these discussions often leave out is, what exactly is a critical mass point anyway? How do you know where it is, and how do you know if you’ve hit one?

To answer this question, let’s return to the original definition of “critical mass” from the Physics world:

The smallest mass of a fissionable material that will sustain a nuclear chain reaction at a constant level.

What does fissionable material means? What is the chain reaction that happens for a web property? Let’s look at it from two separate contexts – user acquisition and retention.

User acquisition
One way to interpret this is that initially, your site has difficulties with user acquisition, until you hit some scale points in terms of total userbase. Then all of a sudden, your site goes “viral” and you start getting lots of users coming in. To formalize this idea, you could imagine the following happening:

Initially, you are getting users through ads or PR, and your viral factor is <1

As your site grows, word of mouth effects (bloggers, friends, etc) give you some name recognition

This brand recognition increases your conversion rates across the board, thus boosting the percentages that make up your viral factor, increasing it to >1

That’s one way of viewing it, although I don’t believe that’s what most people mean. They usually mean that their site is not that useful until there’s a certain # of people on it, and when you cross the critical mass point, then the site becomes engaging. So let’s talk about this idea in an engagement context:

Engagement
As discussed above, there’s an idea that for a user-generated content site, you have an early bootstrapping problem. If you’re YouTube, but have no content, then no users will stick around. Yet if you have no users, then you have no one to upload content. So you need to break out of this local minimum until you cross some threshold – this is the critical mass point. To formalize this idea, here’s the retention focused view:

Early on, you are getting users through PR or ads, but all your users bounce off the site

However, each user you acquire have some chance of creating content (profile/pictures/video/etc)

Eventually, new users have enough content to consume that they stick around on the site, perhaps messaging older users, who now return

Once you have a “critical mass” of users, then there’s enough activity to keep everyone coming back

In this perspective, you can imagine that there are actually multiple phases that your user passes through – initially, they have a passive experience where they are pulled back onto the site because of notifications like friend adds, messages, etc. And it’s possible for your site to never get past this phase. However, if you acquire enough people, new users pull back old ones, who then start coming back, until they start using the site on a regular basis.

What “scale” of network does your website depend on?
However, the discussion above also neglects that users want to consume different kinds of content depending on how they view the site. For example, the following scenarios are probably FAIL states, even if on the surface they look good:

1,000,000 users composed of 100 strangers in 10,000 different locations

1,000,000 users who created 1,000,000 different forums with no cross-visiting

The reason is that the above scenarios represent ultra-fragmentation, with no ability to reach critical mass points. This illustrates that there are different scales of network, which reflect different product designs. These include:

Networks of “real friends”

Networks of online friends united around an activity or interest (WoW, anime, etc)

Networks of people in the same local region

etc.

It takes careful thought to figure out what network your product is really built on. It’s very common to see companies that are primarily targeting purely online friends build features that are really meant for people that know each other offline.Similarly, even within a type of network, it’s important to consider the level of adoption within that network. You could argue that there’s a concept for a “minimum social group” which represents the smallest number of friends within the appropriate network, before a social tool is useful. This minimum social group concept is kind of interesting because
some applications only need a small number of friends to get off the
ground, and others need more:

Skype: 2 minimum

Mailing list: 4-5 minimum

Forum: 10 minimum

Social network: 10? 15? 20?

… etc.

So I’d encourage anyone building a social site to really consider what type of network they are building for, and how many people they need at the local level. Once you can figure that out, then the next goal is to aggregate these smaller groups into a larger one. This is essentially what Facebook did – by understanding how to dominate a smaller space like a college, they could roll up lots of small spaces into a larger population.

Aligning your user acquisition to your network goals
As many have observed, startups working on the Local space have had a very very tough time, with the exception of Yelp. In Seattle, where I’m from, Judy’s Book raised a ton of money and then promptly closed shop because it was hard to get traction.

The reason of course, is that a regional network is a pretty specific one – there are tons of them – plus the minimum social group is actually pretty high. You need a lot of diverse people on the site, reviewing everything in site, before you hit a reasonable coverage % for reviews.

Similarly, if you are doing blind addressbook importing as the way to grow your userbase, but you aren’t targeted about what traffic you’re pointing into the viral loop, then you might end up with a bunch of users from Turkey or some other random part of the world. Probably also not what you wanted.

So to review:

Critical mass is defined by what type of network your social product operates on, and how many users you need on that network before the product becomes useful

Thus, critical mass is a product-by-product discussion – there’s no one-size-fits all

Similarly, people that use your product go through a collection of “phases” – from ranging from passive usage where there isn’t enough content to consume, to the point where they are very active and creating content themselves. The threshold point between the phases is a local observation of critical mass

Sites that are useful for “online friends” and don’t require too many people are the easiest to get off the ground (but have other issues, like they might be too niche)

Site that are useful only for large numbers of “real life friends” (local review sites are a good example) are the hardest to get off the ground, yet are hugely useful if you can get people on board